1. Field of the Invention
The preset invention relates to a wireless communication system. More particularly, the present invention relates to an apparatus and method for providing relay services in a wireless communication system using a relay scheme.
2. Description of the Related Art
In a communication system, signaling and data traffic is exchanged between a fixed Base Station (BS) and a Mobile Station (MS) over a direct link. Much research has been conducted to provide increased MS mobility and flexibility as per a configuration of a wireless network in a communication system, and to provide more efficient services in the wireless environment in which a change in traffic distribution and call demand is significant. One of the communication systems under study is a relay communication system employing a multi-hop relay-type data transfer scheme that uses a Relay Station (RS). The relay communication system may reconfigure the network in quick response to a change in a communication environment, making it possible to efficiently operate the entire network.
FIGS. 1A and 1B illustrate interference occurring in a wireless communication system and a relay communication system, respectively according to the related art.
Referring to FIG. 1A, a MS1 102 is served by a BS1 101, and a MS2 103 is served by a BS2 104.
While the BS1 101 is in communication with the MS1 102, the MS2 103 may transmit a communication signal to the BS2 104. In this case, however, a signal from the MS2 103 to the BS2 104 may interfere with the signal between the MS1 102 and the BS1 101.
Likewise, while the BS2 104 is in communication with the MS2 103, the MS1 102 may transmit a communication signal to the BS1 101. In this case, a signal from the MS1 102 to the BS1 104 may interfere with the signal between the MS2 103 and the BS2 104.
Referring to FIG. 1B, while a BS 111 is in communication with a MS3 112, a MS4 113 may transmit a communication signal to an RS 114. In this case, a signal transmitted from the MS4 113 may interfere with the signal between the MS3 112 and the BS 111. Likewise, while the RS 114 is in communication with the MS4 113, the MS3 112 may transmit a communication signal to the BS 111. In this case, a signal from the MS3 112 may interfere with the signal between the MS4 113 and the RS 114.
In these related art communication systems, timing in an Uplink (UL) is controlled in order to reduce interference signals in a BS and adjacent stations, such as another BS or RS. To this end, there is a need to efficiently configure UL frames used in the RS.